Single Root I/O Virtualization (SR-IOV) is a specification that allows a Peripheral Component Interconnect Express (PCIe) device to appear to be multiple separate physical PCIe devices. SR-IOV enables a virtualization intermediary (VI), such as a hypervisor or virtual input/output (I/O) server operating system, to configure an I/O adapter into a number of virtual functions (VFs). The virtual functions may be assigned to different operating system images (OSIs), or logical partitions (LPARs).
The virtual functions belong to a PCI hierarchy and are of a device type that may be undefined in operating system and system firmware. Configuration of the virtual functions may require significant administrator man-hours and system downtime. Association and management of the virtual functions with a PCI adapter or adapter slot location that is subject to PCI adapter maintenance and administrative operations, such as adapter hot plug and dynamic assignment to or from logical partitions, may be undefined in operating systems and system firmware.